I don't have any diabetes complications, either. I pretty much have all of the problems that you have.
My endocrinologist ordered the test. The blood can be drawn at any draw station (Quest/LabCorp/other lab) and the blood needs to be shipped on ice to the Mayo Clinic Laboratories in Rochester, Minnesota. Only 50-60% of those with the disease actually have the antibodies. It's really rare.
If you do not test positive for the antibodies, there are some other specialized tests that can be ordered to diagnose autoimmune autonomic neuropathy, as there are unique features to this particular disease, autoimmune autonomic ganglionopathy. (You have to pay for the article--unless your doctor, who probably has access to this article, prints it off for you.) http://www.ncbi.nlm.nih.gov/pubmed/19155193
My neurologist specializes in autoimmune neuromuscular disorders. Any neurologist who specializes in neuromuscular disorders is likely suitable, but ideally, you want a doctor who is a diplomate in Autonomic Disorders. https://www.ucns.org/globals/axon/assets/10297.pdf